Initial experimental results of CAEP photoinjector

An RF photocathode gun which, along with a compact linac, forms the injection system for a planned FIR FEL amplifier experiment, has been commissioned in the high power radiation laboratory. This high-gradient gun has emitted 60 ps, 10 A electron beams of up to 3 MeV energy. These beams have been characterized by a variety of diagnostics. The quantum efficiency of Cs2Te has been measured at normal incidence. The energy and energy spread of the beam were tested using a dipole spectrometer, while the time structure was examined with a picosecond resolution streak camera. The emittance of the beam was measured using the pepper pot technique and its dependence on space charge and RF phase were found. The impact of these results on improving the design and operation of this high brightness photoinjector is discussed. This injector will be applied to the FIR FEL project in future.